Populations of wild animals have plummeted 58 percent in the past four decades as humans have pushed them into ever-smaller habitats or killed them for food and financial gain, according to a new report from a leading environmental group.

World Wildlife Fund researchers said the losses could be reversed over the 21st century by systematically factoring the value of nature into how we produce and consume goods and services, as well as adopting farming methods that work with ecosystems rather than against or in spite of them.

WWF compiled data on more than 14,000 populations of 3,706 vertebrate species for the latest edition of its biennial Living Planet Report and found that global populations of amphibians, birds, fishes, mammals, and reptiles sank by an average of 58 percent between 1970 and 2012. These populations could drop another 9 percent by 2020 based on current trends, the report stated.

Freshwater wildlife populations dropped a dramatic 81 percent—meaning that for every 10 pond frogs that existed during Richard Nixon’s first term in the White House, there were fewer than two at the beginning of Barack Obama’s second.

Terrestrial and marine species populations dropped by 38 percent and 36 percent, respectively, over the same period.

The leading driver of wildlife population losses has been food production—overfishing and natural habitats converted to crop and grazing land—followed by pollution, invasive species, and climate change. All five threats are symptoms of overconsumption of natural resources, the report stated, which has far outstripped the capacity of ecosystems to restore the fertile soil and clean water that support wildlife as well as human health and welfare.

“Humanity currently needs the regenerative capacity of 1.6 Earths to provide the goods and services we use each year,” the report noted, and the short-term goals of most economic systems offer no incentive to change.

But case studies included in the report suggest that if a longer view is taken, there are many ways to provide for human welfare while also conserving biodiversity.

One example is the recent removal of two hydroelectric dams along Washington state’s Elwha River. The restoration of free-flowing water has spurred a return of the river’s chinook salmon, a keystone species for the region’s freshwater and forest ecosystems that is also prized spiritually, culturally, and as a food source by the native Klallam people.

“The Elwha is an example of where we estimated what’s the value of a free-flowing river,” said John Loomis, an expert on environmental economics at Colorado State University, “especially to salmon and to tribal values—both economic and cultural values—and included that in the environmental impact statement” for the project.

That changed “the nature of the debate from being one of the economy versus the environment,” he said, to one that links the two and demonstrates that they are interconnected.

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“The question is going the next step and saying, ‘These ecosystem services have dollar values,’ ” said Loomis, who conducted an analysis of the dams’ removal that found taking them down would generate $3.5 billion in noneconomic benefits. “Once we incorporate those, we see that doing agriculture the cheapest way possible, or producing goods in the most profitable way, doesn’t incorporate these environmental costs. We need to shift our production and consumption to account for these costs [and] not squander that natural capital by treating it as having zero value.”

In another case study, the report noted Malawi’s switch from subsidizing chemical fertilizers to agroecology farming methods, which apply ecological principles to agriculture. For instance, combining crops to increase plant and soil diversity doubled or tripled harvests of maize, a staple crop for the country’s poorest citizens.

“The more we design that system to be similar to how nature’s designed, the better chance of that agricultural part of the landscape functioning as the natural landscape does in supporting wild animals,” said Steve Gliessman, a professor emeritus of environmental studies at the University of California, Santa Cruz, and cofounder of the nonprofit Community Agroecology Network. The group works with farmers in developing nations to adopt agroecology, which also entails creating stable markets and getting more equitable compensation for their crops. Gliessman’s research was cited in WWF’s report.

Environmental groups can’t protect wildlife “just by putting up fences and walls that keep people out of natural areas, and ignore the pressures beyond those fences that drive people into those areas,” he said. “We’ve found that diversified farms in coffee plantations in Nicaragua and Mexico, [with] multiple layers and multiple species in the canopy, helps provide habitat and, if bordering a reserve, takes pressure off the reserve.”

In the United States, agricultural policies are a barrier to agroecology, and “a lot of the externalities caused by modern farming, like soil erosion or wildlife loss, aren’t factored in,” Gliessman said. “Most of the farm bill supports the opposite. I like to say it should be a food bill that integrates agroecology and a different incentives and awards system. In the U.S., right now we can do it only mostly through consumer awareness.”

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